Gliffy is an online diagram service that lets you create charts, flow charts, wireframe models, business process models and other similar things. It is more commonly used as a generic visio replacement. It works on the browser and you can create stuff before you even have to sign up. There are free accounts and premium accounts. It seems to work well at this point but it crashed after I tried to save the document I was working on. Good thing I was only testing it. If this is just a glitch then this software is definitely worth a look if you dont want to shell out big bucks for Visio.